Better late than never.
19. d2e4  19... b7b6 But here the Chinese GM misses an important detail. 20. d1e1 A star move $1 The main threat is Ne4xc5 $1 with the total collapse of the opponent's queenside. 20... e6c6  21. e4d2 A second sudden retreat, and the knight is shifted to its optimal position.